The latest FID Editor that I've been able to find is GroupWise 5.x Archive FID Editor 1.0; and although it only says GW5.2 and GW5.5, other TIDs suggest that it will work with GW8.x!
Is there a newer editor or can this be used?
As a follow-up question, does the editor change more than the Folder/File names to make sure they all have the new FID in their names?